A flip chip bonding method of forming a solder film over a tip of a pillar of an electrode on a chip, flipping the chip and pressing the solder film formed over the tip of the pillar onto an electrode of a substrate, and heating and melting the solder, thereby mounting the chip on the substrate is widely used. An apparatus for mounting a chip on a substrate by flipping the chip in this manner is called a flip chip bonder.
In the flip chip bonding method, a plurality of electrodes of a chip are joined with a plurality of electrodes on a substrate at the same time. Accordingly, it is important to maintain the substrate and the chip to be parallel with each other, so that surfaces of solder films formed over tips of pillars of the electrodes of the chip are brought into contact with the electrodes of the substrate at the same time. Therefore, a flip chip bonder is required to have a bonding stage whose surface is highly flat. Further, it is also required that the surface of the bonding stage is heated uniformly, as it is necessary to press the solder films formed over the tips of the large number pillars onto the electrodes of the substrate, and to uniformly heat the solder to melt at the same time. Moreover, a force required for pressing the chip onto the bonding stage during bonding increases as the size of the chip to be bonded increases, the bonding stage is required to have high rigidity at the same time.
Therefore, there is proposed a method of ensuring flatness of a bonding stage by supporting the bonding stage for suctioning and holding a substrate using three support mechanisms capable of moving the bonding stage in an up-down direction, and adjusting an inclination of a surface of the bonding stage, so that parallelism between the bonding stage and the bonding tool are maintained (e.g., PTL 1 and PTL 2).
Further, a wafer heating apparatus is used in order to heat a semiconductor wafer during processes including formation of a semiconductor thin film, etching, and printing of a resist film in semiconductor fabrication. Such a wafer heating apparatus is required to uniformly heat a wafer placed on its surface, a method in which a heater is provided under a lower surface of a ceramic plate on which a wafer is placed to uniformly heat the ceramic plate is employed (e.g., PTL 3).